T lymphocytes are involved in many immunological reactions, and the various T cell subclasses are capable of performing different specialized functions. Biochemical reactions must be involved in regulating the functional differentiation of T cells. Since S- adenosylmethionine (AdoMet) is one of the most pivotal molecules in biology and is of central importance in cellular regulation, we will study the metabolism of AdoMet in functionally distinct human T lymphocyte populations. As a model system, the interactions of human T lymphocytes with the well-defined antigen, surface M protein of (type 5) group A streptococci will be studied and compared to their interactions with polyclonal mitogens. The role of AdoMet and polyamines in T cell blastogenesis in response to nonspecific polyclonal mitogens has been studied. However, few studies have investigated either the role of AdoMet or polyamines in specialized T cell functions (e.g. help, suppression and specific cytotoxicity) and nothing is known about AdoMet metabolism in various T cell subsets. In this study, specific efforts will be directed towards: One, comparing the effects of a specific antigen (M5 protein) and nonspecific, polyclonal mitogens (PHA or Con A) on AdoMet metabolism in lymphocytes. Two, comparing AdoMet and polyamine metabolism in functionally distinct T cell subsets. Three, studying the effect of inhibition of polyamine and AdoMet synthesis and utilization on T cell subset composition and functional differentiation of M5 stimulated T cells. These studies will determine the utilization of AdoMet via either methylation or polyamine biosynthesis and will include measurement of the level and turnover of the enzymes and metabolites involved and correlating the changes in the kinetic of AdoMet metabolism with the changes in the T cell response (blastogenesis as well as specialized T cell functions. T cell subsets will be separated by methods which exploit differences in their surface markers. Functional studies will include the ability to help or suppress B cell differentiation in response to Pokeweed mitogen (PWM) and the ability of M5 protein stimulated T cells to kill myocardial cells. Metabolic inhibitors of either synthesis or utilization of AdoMet will be used to determine the role of AdoMet and its metabolites in the various phases of T cell functional differentiation. These inhibitors will be evaluated according to a set of criteria designed to determine their specificity and mode of action. The outcome of the proposed study should increase our understanding of biochemical regulation of T lymphocytes and should set the foundation for our long-term goals which include studying the role of AdoMet metabolism in T cell functional differentiation and the regulation of gene expression in T cell subpopulations. In addition, studies of biochemical reactions of T lymphocytes is considerably important not only for understanding normal immune regulation, but also for abnormal immune responses and imbalances in T cell regulatory functions which can cause diseases such as autoimmunity or immune deficiency.